Method of treating paper board



Sept. 6,1927. v D HNLEY 1 641,479

METHOD OF TREATING PAPER BOARD Filed June 13, 1923 5'5 5 INVENTOR. Fig 4 1202/51? F/IVLEY A TZORNEYS.

Patented Sept. 6, 1927.

UNITED STATES PATENT, OFFICE.

IDOZIER FINLEY, OF BERKELEY, CALIFORNIA, ASSIGNOR TO THE PARAFFINE COM- PANIES, INO., OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF DELAWARE.

METHOD OF TREATING PAPER BOARD.

Application filed June 13, 1923. Serial No. 645,088.

The invention relates to the production of paper board of a water-proof and greaseproof character, and one of the ob ects of i the invention is the production of a paper a board, processed with parafiine, which during the process undergoes a minimum of discoloration or a controlled discoloration. Another object of the invention is the provision of aprocess whereby a parafline 1 treated paper board or paper board articles of handsome appearance may be produced from a relatively inexpensive grade of paper p board.

Another object of the invention is the provision of a process of paraffinmg paper board which may be carried out without painstaking control of temperature and-the chilling bath, and which produces a more brilliant, and in the case of white coated board a whiter product, than is possible by vformer .methods. Afurther object is the conservation of the more valuable materials used in producing this general class of paper board. Other objects of the invention together with the foregoing will be set forth in the following description of the preferred process and the means forplracticing the-same, which is illustrated in e drawings accompanying and forming-part of the spec1fication.- It is tobe understood that I do not limit myself to the :showing made? by the said descriptions andjdrawings, .as I may ado t variations of my preferred form within t e scope of my invention as set'forth m the claims.

Referring to the accompanying drawings: Fig. 1 is asectional View of apiece of board of my invention. The view is largely d a grammatic and certain portions have been 40 emphasized out of their true proportion in order to make the structure 'clear. Fig. 2 illustrates. diagrammatically one method of carrying out t e operationsinvolved in my invention and Fig. 3 illustrates another method.- Fig. dis a lan view of a piece of my paper board illustratinga decorative efiect, which it is possible to secure in the practice of my invention. Fig. 5 illustrates diagrammatically an apparatus by which the decorative efiect shown in Fig. 4 ma be secured, and Fig. 6 is a side elevation 0 one of the rolls forming part of such apparatus.

In the making of many types of paper board packages, popularly known as cartons,

i it has been the custom to coat the paper board with parafline wax, preferably meltng at about 130 Fahrenheit, and applied 1n the molten state by a variety of methods WlllCh are well understood and need not be explained here. The thickness of the parafline coating adds about two-thousandths of a millimeter to the thickness of the paper board, and this is divided between the two sides. Not all of the parafline is superficially coated upon the boards' Some of it soaks into the boards to a slight extent. A aper board comprising a straw colored filler and a white liner and having a thickness of approximately nine-thousandths of a millimeter when paraflined, shows a mottled effect, proving that the parafline has penetrated the thinner part of the liner sufliciently to render it translucent. A board having twice the thickness of white liner will not show this mottled effect. This is indicative of a penetration of parafline rang ing between six and twelve-thousandths of a millimeter.

If the board, just previous to the application of 1piiarafiine, is Wet with water and then super cially dried it will be found that there is adiminished penetration of the parafiine as indicated by no evidences of discoloration. It is diflicult, however, to con-' trol the wetting ofthe board so as to secure uniform results. If the board is too wet there is the possibility that the paraffine will not adhere to the surface, and if too dry penetration of irregular character will result.

I have found that if the board is wet with water containing dissolved gums, sugars or salts, a more even control is obtained. In such a case all of the water employed may1 be permitted to evaporate and a film of t e previously dissolved matter is left on the surface of the board. This film is suflicient to reduce or prevent penetration of the melted parafline into the outer structure of the paper board. It should be noted that it is not necessary to dry the board thoroughly before the parafiine is applied.

In fact, in a continuous process it is referable that the thorough drying out o the water be not sought, or that drying be obtained only so far as permitted by the limitation imposed by continuous operation.

A solution for treating the aper board which I have found very satis actory comprises the following materials: 12 gallons of III water, 20 pounds sodium chloride, 27 pounds saccharose, 54 pounds glucose (from starch), 3 pounds sodium borate. The solution will be found to be just short of a syrupy consistency and to contain practically half water and half solids. It may be applied to the surface of paper board by saturating a cloth with the solution and rubbing the solution wetted cloth'over the paper board which is then allowed to dry. \Vhen dry or practically dry, the board may be passed into a paraffining machine of known type and given a coating of parafiine over the solution treated surface. This method is suitable for a small amount of the paper board but on a large scale I prefer to follow one or the other of the following methods.

First method-This method is especially adapted to the treatment of paper board on which discoloration is to be prevented on only one side, and is essentially a discontinuous process.

. The board is first passed thru a set of rolls and given a parafiine treatment on the side on which discoloration is of no importance. This is the ordinary operation familiarly known as parafiining one side. The board is now passed thru a set of rolls as illustrated diagrammatically in Fig. 2, in which the lower portion of a rubber covered roll 3 lies in a solution 4, prepared according to the above formula and contained in a pan 6. The roller 7 is adjustably held by well known means in such position above and relative to the roll 3, that only enough of the solution is permitted to be deposited on the board 8 to make the board wet and tacky to the touch without being flood coated. The greater part of the excess solution taken up from the tank 6 by the roller 3 is kept back by the doctor or scraper 9 thus protecting the roll 7 from becoming wet. A further protection for the same purpose is furnished by the doctor or scraper 11.

In the practice of my invention 1 have found that quantities ranging around of an ounce of solution per square yard are sufficient, varying of course according to the porosity of the surface of the board. Sheets of board thus treated may be stacked or piled'one on top of the other, although still wet on the solution treated sides, and the same applies to board which is treated in the roll, that is, it may be rolled up on a spindle without danger of sticking. Although the solution in drying becomes tacky or sticky it will not adhere to the contiguous parafline coated surface. It will usually be found that the solution becomes dry in the time the board is stacked or rolled up. This is due to the water distributing itself thru the body of the board, and being held hygroscopically by the fibers, while the salts and gums and sugars of the original solution remain as a film on the surface of the board.

The board as treated in the above described process is next passed thru a second parafiining operation by which the solution treated side is coated with parafline. It is obvious that paratlining may be on one or both sides. ll on both sides, the paraftine of the first treatment is not appreciably augmented by the second treatment since it is largely remelted and displaced in part by new paraffine and in part remains in situ.

It will of course be appreciated that the board mav be dried by evaporation of the water of the'solution if the sheets are spread out singly or if they are put into or passed thru a drying chamber.

Second methorl.Tl1e second typical process for carrying out the invention is practiced with an apparatus illustrated in Fig. 3. This is essentially a continuous process, and is adapted to the treatment of one or both sides of the board with the solution. This apparatus includes two sets of wringer rolls, one set comprising the rolls 13 and 1 and the other set comprising the rolls 15 and 1G. The lower rolls l4: and 16 are partially immersed in the above described solution 17 contained in pans l8 and 19 respectively. Each of the rolls is provided with a doctor or scraper 21 to prevent excess solution being carried upwardly from the tanks upon the boards. The top rolls 13 and 15 are also provided with doctors or scrapers 2:2, and supply spouts 23 suitably valved are provided for carrying solution to the upper rolls. Preferably all the rolls are of rubber and are geared to run in the direction i11- dicated. Means well known in the art are provided for adjusting the relative position of the rolls in each set and resiliently retaining the rolls in relative position by springpressed bearings.

The sheet of board 26 passing between the rolls, and coated on each side with a film of the'solution, is received on a carrier belt 27, which passes over a heating coil or means '28. The hot air currents from the heating means help to evaporate the moisture from the solution on the board passing above. From the carrler belt 27. the board passes between the paraflining rolls 30, where it 1 receives a film of the melted parafiine in a manner which will be understood by those skilled in the art. From the parafiining rolls the sheet passes into the water filled chilling tank 31 where the parafiine which has ust been applied by the rolls is suddenly chilled so that a glazed finish is produced, without that crystallization which causes a more or less milky appearance.

- In Fig. l, I have shown in diagrammatical. form and somewhat exaggerated, a section of paper board treated by my process. The body of the board 35 has been given a coating or film of the solution which has dried and left a residue 86 of the soluble materials carried by the solution dc osited on and saturated into'the surface the board. Over the solid material deposited on the board a thin film 37 of parafline imparts a glazed finish to the board, which is both grease and water resisting. It will be noted that the parafline layer 37 is not shown as having penetrated into the board and because of this lack of penetration no discoloration or mottled efiect occurs.

lln Fig. 4 l have shown a plan view of a piece of board in which predetermined areas of the surface have been coated with the solution referred to above, so that when the paraffine is subsequently applied, the lack of absorption of the parailine over the treated areas and its absorption in the untreated areas give rise to a pattern or decorative efi'ect, which cannot be secured otherwise except by means which it is not practicable to use. lln the diagonal line or lattice pattern shown in Fig. 4a the areas 38 are the treated areas, and the areas 39 are the untreated areas, the untreated areas absorbing the paraffine more or less and hence taking on a darker shade than the treated areas. ()bviously, variation in these decorative effects is infinite and trade-marks and insignia suggestive of water marks as Well as other designs in a wide variety may be thus tensities may applied in an attractive way.

In Figs. 5 and 6 l have shown'in diagrammatic form an apparatus for applying m solution to secure a decorative effect. I sheet of paper 41 passes between the rollers 42 and 43, the upper of which has a plain face, and the lower provided with a resilient water insoluble facing such as rubber, and having the desired design molded or otherwise arranged thereon in relief as shown in Fig. 6. Solution from the pan 4A is carried up to the roller 43 by means of the roller 45 which acts like an inking roller. The amount of solution provided on the roller 43 is controlled by the doctor 46 arranged adj acent the roller 45.

If "desired, dyes ofvarious colors and inbe added to the solution to secure an enhanced decorative eifect.

As indicated in the above description a wide range of concentration is possible in the coating solution. Not alone is this infiuenced by the texture of the board to be treated but different concentrations may be used on the same board. As noted, a mere wetting of the board with water will pre-e vent the undesirable soaking in of the paraffine although it does not permit the desired close control. In a broad sense it may be stated that the .use of a fluid'varying from water to a solution in which there is a concentration of 50% or more of solids,

will effect the purpose of the invention.

The upper limit of concentration appears to be that at which the solution becomes too water.

viscous to work properly. However, with the application of more pressure upon the wringer rolls, the amount of even a very viscous solution applied to the surface of the board may be 'reduced to a workable quantity.

The ingredients of the solution are also capable of variation within a wide range. Casein may be used in the solution, preferably the mildly alkaline soluble forms of casein. Flour or preferably starch may be used, either in the cooked or uncooked state. So also molasses, dextrine, animal glue, and where alkali will not affect the board or the printing thereon in an undesirable manner, silicate of soda may be used. Any of these materials may be mixed with'water, or combinations of them may be mixed in water in any desired concentration not having too high a degree of viscosity.

Since paper board cartons are very largely used for-the packaging'of food stufi's, it is desirable that the ingredients of the solution used on them shall be nonpoisonous. The ingredients I have named in the preferred form of the solution are not only non-toxic but with the exception of borax are common ingredients of food stufls. Borax is commonly used in the dextrine paste for cementing the cartons, and is as well known perfectly harmless unless taken into the human system in' considerable quantity.

Instead of sodium chloride, ammonium chloride may be used in the proportion of about 2 /270 by weight in the solution; The distinctly saline tasteof sodium chloride or ammonium chloride makesthe solution distasteful to flies which might be attracted by the sweetness of a glucose and su ar solution. The sugar or saccharose is used cause it is a common ingredient of food stufls, is relatively cheap, and is extremely soluble in V Glucose is used because it inhibits the crystallization of the other ingredients when the water evaporates and because it is common in food stuffs and is relatively cheap. The borax serves as a preservative to prevent solution should be thinned to apoint where ferments could act..

I have found that other solutions than those having a water solvent may be used in 1 carryingout my process. Among them may be mentioned nitro-cellulose solutions and all of the class of solutions having a base of nitro-cellulose and having admixtures of other substances, such as castor oil, gum camphor, and tung oil. While such solutions are relatively more expensive than the water solutions above described, yet an extremely small amount of the mtro-cellulose film is effective in stopping the absorp-- tion of the parafline.

Instead of applying the solution in the fermentation of the sugars if the manner illustrated and described it may be applied totheboard by, means of spray po zzles or brush machines of well known orm.

'to employ fillers in the solutions, such as china clay, or whiting for the purpose of filling the pores in the surface of the board, to

1 obscure the printing. Usually I find it 7 inadvisable to treat the board previous to printing. It is possible to use the solution in all workable concentrations on board which has been printed and my process is especially intended to follow the printing I of the stock and immediately precede the parafiining operation. Following the first method herein set forth and allowing the Under some conditions it may be-desirable board to dry, 'or using the nitro-cellulose solution, it becomes. possible-and is in some 'instances advisable to print. the-board after,

instead of before treatment with the solution. I claim: e f 1; The method of treating paper board which com rises applying thereto an aqueous 1 solution 15 sodium. chloride, saccharose, starch glucose and sodium borate and subsequently coating the surface with parafiinez.

2. The method of treating paperboard which comprises applying thereto a solution made substantially in accordance with the following formula: 12 gallons water, 20 pounds sodium chloride, 27 pounds sacchav rose, 54 pounds glucose, .3 pounds sodium.-

borate and subsequently coating the surface with parafline.

In testimony whereof, I have hereunto set my hand.

DOZIER FINLEY. 

